Magnesium base alloy



Patented Apr. 7, 1941 I UNITED STATES PATENT OFFICE John C. McDonald,Midland,

The Dow Chemical Company,

Mich., assignor to Midland, Mic

a corporation of Michigan No Drawing. Application October 4, 1940,Serial No. 359,680

4 Claims. (CL 75-168) The invention relates to a magnesium base alloy.It more particularly concerns an alloy of this nature having improvedphysical properties nesium and, at the same time, possesses superiorstrength properties, rendering it useful for making castings, forgings,and the like, wherein light weight is oftentimes highly desirable.

Other objects and advantages of the invention will be apparent as thedescription of the invention proceeds.

My invention resides in the discovery that a magnesium base alloycomposed of from 0.01 to 3.0 per cent palladium, the balance beingsubstantially all magnesium, possesses the aforementioned propertiesto amarked degree. The

term magnesium used herein and in the appended claims is intended toinclude magnesium containing the ordinary impurities that are found inthe commercially pure metal, such as traces of iron, copper, nickel, andsilicon. While the properties of high tensile and yield strengths aremanifest over the entire range of composition indicated, in generalit'has been found that the preferred combination of properties such-asthe most desirable yield strength, coupled with correspondingly hightensile strength is found in those alloys containing from about 0.1 to2.0 per cent palladium. A preferred alloy having the most desirablecombination of yield strength and tensile strength in both the annealedand cold rolled state is one containing about 0.3 per cent palladium.

The following table which lists some of the properties of rolled sheetmetal made from my new binary alloy and comparesthese properties withthose of commercially .pure magnesium, illustrates the improvement inyield strength and tensile strength of mynew alloy over that of thecommercially obtainable magnesium. The'magnesium used in preparing thenew alloy and for the purposes of comparison was obtained by sub limingcommercially available magnesium.

Table Nominal com. Annealed Cold rolled positiont Yield Tensile YieldTensile (magnesium' stren h stre h strength strength mmaigdm mu inii01103.1 inlbs.

sq. in. sq. in. sq. in. sq. in

The properties set forth above under the m anneal were obtained by firstrolling the specimens at a temperature between 600 and 700 1'. andthereafter annealing them at various temperatures through a range orfrom 400 to 800 F. The properties selected for the table were those ofthe annealed specimens showing the maximum ductility or formabllity asmeasured by the per cent elongation. The properties set forth undertheterm "cold rolled were obtained by subjecting specimens which had beenfirst hot rolled at temperatures of from 600' to 700 F. to additionalrolling in the cold state.

The properties selected for the table were those of the cold rolledspecimens which showed the highest tensile and yield strength, whilehaving at least a 1 per cent elongation in 2 inches;

A comparison of the properties listed in the table shows that the yieldstrength and tensile strength of the new alloy are. markedly superiortov similar properties of sublimed magnesium in both the annealed andthe cold rolled state. This improvement is exhibited throughout therange of composition indicated.

The new alloy will be found to be most useful for making castings,extruded forms; and the like, due to its high tensile andyieid The newalloy may be compounded byi' any of the methods used for melting andalloying metals with magnesium, such as by adding the palladium to abath of molten magnesium which is preferably protected from oxidation bysuitable flux.

Iclaim: 1. A magnesium base alloy containing from 0.01 to 3.0 per centpalladium, the balance being 4. A magnesium base alloy containing from0.01 to 3 per cent 01' palladium and characterized by a substantialimprovement in at least one of the properties ductilit y, tensilestrength, and

5 yield strength as compared with magnesium without the palladium.

' JOHN C. MCDONALD.

